Location: Crop Germplasm Research2010 Annual Report
1a. Objectives (from AD-416)
Objective 1: Develop and evaluate improved grass germplasm for the southern U.S. that is more productive, biologically diverse, tolerant of biotic and abiotic stresses, improved in quality, and easier to establish and maintain in pastures and rural landscapes. Sub-objective 1.A: Develop and evaluate kleingrass (Panicum coloratum) germplasm with improved forage yield, seedling vigor, and persistence. Sub-objective 1.B: Produce intraspecific Paspalum hybrids between different dallisgrass biotypes to develop improved forage types. Sub-objective 1.C: Identify superior Texas bluegrass (Poa arachnifera) genotypes that are rust resistant and adapted to the humid southeastern U.S. to develop a synthetic population from these genotypes. Objective 2: Use genomic techniques to develop and identify molecular markers associated with traits of interest in forage and turf grasses. Sub-objective 2.A: Identify molecular markers to further saturate the genomic region controlling apomixis and survey candidate genes for seed sterility in buffelgrass (Pennisetum ciliare). Sub-objective 2.B: Develop a genetic map of dallisgrass (Paspalum dilatatum) to identify markers linked to apomixis, disease and insect resistance, and other traits of interest. Objective 3: Develop improved breeding methodologies by determining the cytology, reproductive biology, and genetic diversity of native and introduced germplasm for the production of improved forage and turf grasses. Sub-objective 3.A: Determine the method of pollination, chromosome number, ploidy level, and mode of reproduction of species in the genera Panicum, Paspalum, Pennisetum, Sorghum, Chloris, Setaria, Stenotaphrum, Tripsacum, and others to facilitate their genetic improvement. Sub-objective 3.B: Determine the genetic diversity and phylogeny of Paspalum and Pennisetum species using DNA fingerprinting techniques.
1b. Approach (from AD-416)
The long-term objectives of this project are to obtain a better understanding of the cytology, reproductive biology, and genetic diversity of selected forage grasses, and to use this fundamental information in the breeding and development of superior germplasm that will be released as improved cultivars.
3. Progress Report
During FY 2010, research under this project continued to make advances in developing and selecting superior germplasm that will be used to develop improved forage grass cultivars. Open-pollinated seed was harvested from 12 elite kleingrass (Panicum coloratum) selections growing in a replicated polycross nursery; this seed will be used to establish forage evaluation tests at multiple locations to determine if this germplasm is superior to existing kleingrass cultivars. A second replicated polycross block of 10 kleingrass genotypes with an upright growth habit was established to develop germplasm with a more uniform upright growth pattern. Open-pollinated seed was collected from each of the 24 genotypes that make up the switchgrass (Panicum virgatum) germplasm line "TEM-LoDorm" to provide seed of this unique germplasm line to other plant breeders working with this species. This germplasm line has low seed dormancy and is of interest to grass breeders working with this species. Seedlings from controlled crosses between the yellow-anthered and Uruguayan dallisgrass (Paspalum dilatatum) biotypes were germinated and transplanted into an evaluation nursery for the purpose of identifying the hybrids. Sixty-nine Texas bluegrass (Poa arachnifera) genotypes were selected from a germplasm evaluation nursery at Rosepine, Louisiana, on the basis of their vigor and superior traits. Some of these plants will be used to expand the base population in breeding a more productive, rust-resistant synthetic population that is adapted to the humid southeast. In cooperative research with Texas A&M University scientists, cytological studies were conducted to determine the chromosome number of purported sorghum interspecific hybrids to identify the actual hybrids. These hybrids are being used in the breeding of germplasm that will be used as a bioenergy crop. In another cooperative research effort with Texas A&M University scientists, studies were conducted to establish the range and effectiveness of the iap (inhibition of alien pollen) genetic component (allele) in allowing pollen tubes (male) from other grass species outside the genus Sorghum to grow into the pistils (female) of commercial sorghum (S. bicolor). The work showed that the pollen tubes of some grass species readily grew into the ovaries of S. bicolor, which demonstrates that this allele could greatly expand the genetic diversity of this species.
1. Commercialization of Sabine dallisgrass. Cattle producers in the southeastern U.S. have long desired a more productive dallisgrass for planting as a nutritious cattle forage. ARS researchers at College Station, Texas, working with researchers at Texas AgriLife Research and at the Louisiana State University AgCenter, recently released a new dallisgrass cultivar named Sabine and have now successfully grown and collected several hundred pounds of "breeders' seed." Sufficient seed is now available for cooperating commercial seed companies to establish production fields adequate to meet producer needs. Interest in Sabine is already very high among cattle producers in the southeast; in the coming years, this new dallisgrass type will provide producers in the region with a more productive and more sustainable option to common dallisgrass.
Genovesi, A.D., Jessup, R.W., Engelke, M.C., Burson, B.L. 2009. Interplody St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] hybrids recovered by embryo rescue. In Vitro Cellular and Developmental Biology - Plants. 45:659-666.